Raspberry pi with 16x2 lcd display

There are so many example libraries are available...
m also taken from  those examples only..but i modified something and tested lot...

thanks for developers of raspberry pi....

for the connection withe raspberry pi and 16x2 lcd....

pin configuration of the raspberry pi

pin configuration of the16x2 lcd

how to connect the 16x2 display with the raspberry pi

check the code of the python...dump on the raspberry pi

Usually the device requires 8 data lines to provide data to Bits 0-7. However the device can be set to a “4 bit” mode which allows you to send data in two chunks (or nibbles) of 4 bits. This is great as it reduces the number of GPIO connections you require when interfacing with your Pi.

Here is how I wired up my LCD :

LCD Pin	Function	Pi Function	Pi Pin
01	GND	GND	P1-06
02	+5V	+5V	P1-02
03	Contrast	GND	P1-06
04	RS	GPIO7	P1-26
05	RW	GND	P1-06
06	E	GPIO8	P1-24
07	Data 0
08	Data 1
09	Data 2
10	Data 3
11	Data 4	GPIO25	P1-22
12	Data 5	GPIO24	P1-18
13	Data 6	GPIO23	P1-16
14	Data 7	GPIO18	P1-12
15	+5V via 560ohm
16	GND		P1-06

NOTE : The RW pin allows the device to be be put into read or write mode. I wanted to send data to the device but did not want it to send data to the Pi so I tied this pin to ground. The Pi can not tolerate 5V inputs on its GPIO header. Tying RW to ground makes sure the device does not attempt to pull the data lines to 5V which would damage the Pi.

In order to control the contrast you can adjust the voltage presented to Pin 3. This must be between 0 and 5V. I tied this pin to ground.

Pin 15 provides 5V to the backlight LED. It wasn’t clear on my device if this could be connected direct to 5V so I played safe and placed a 560ohm resistor in line with this pin.

Python

You can control a HD44780 style display using any programmming environment you like but my weapon of choice is Python. I use the RPi.GPIO library to provide access to the GPIO.

Here is my code :

#!/usr/bin/python

#

# HD44780 LCD Test Script for

# Raspberry Pi

#

# Author : Durgam anil

# Site   : http://potentialabs.com

# Online Store :http://potentiallabs.com/cart

#more info :anildurgam.blogspot.com

# 

# Date   : 17/12/2013

#

# The wiring for the LCD is as follows:

# 1 : GND

# 2 : 5V

# 3 : Contrast (0-5V)*

# 4 : RS (Register Select)

# 5 : R/W (Read Write)       - GROUND THIS PIN

# 6 : Enable or Strobe

# 7 : Data Bit 0             - NOT USED

# 8 : Data Bit 1             - NOT USED

# 9 : Data Bit 2             - NOT USED

# 10: Data Bit 3             - NOT USED

# 11: Data Bit 4

# 12: Data Bit 5

# 13: Data Bit 6

# 14: Data Bit 7

# 15: LCD Backlight +5V**

# 16: LCD Backlight GND

#import

import RPi.GPIO as GPIO

import time

# Define GPIO to LCD mapping

LCD_RS = 7

LCD_E  = 8

LCD_D4 = 25 

LCD_D5 = 24

LCD_D6 = 23

LCD_D7 = 18

# Define some device constants

LCD_WIDTH = 16    # Maximum characters per line

LCD_CHR = True

LCD_CMD = False

LCD_LINE_1 = 0x80 # LCD RAM address for the 1st line

LCD_LINE_2 = 0xC0 # LCD RAM address for the 2nd line 

# Timing constants

E_PULSE = 0.00005

E_DELAY = 0.00005

def main():

  # Main program block

  GPIO.setmode(GPIO.BCM)       # Use BCM GPIO numbers

  GPIO.setup(LCD_E, GPIO.OUT)  # E

  GPIO.setup(LCD_RS, GPIO.OUT) # RS

  GPIO.setup(LCD_D4, GPIO.OUT) # DB4

  GPIO.setup(LCD_D5, GPIO.OUT) # DB5

  GPIO.setup(LCD_D6, GPIO.OUT) # DB6

  GPIO.setup(LCD_D7, GPIO.OUT) # DB7

  # Initialise display

  lcd_init()

  # Send some test

  lcd_byte(LCD_LINE_1, LCD_CMD)

  lcd_string("Rasbperry Pi")

  lcd_byte(LCD_LINE_2, LCD_CMD)

  lcd_string("Model B")

  time.sleep(3) # 3 second delay

  # Send some text

  lcd_byte(LCD_LINE_1, LCD_CMD)

  lcd_string("Potentiallabs")

  lcd_byte(LCD_LINE_2, LCD_CMD)

  lcd_string(".HYDERBAD,INDIA")

  time.sleep(20)

def lcd_init():

  # Initialise display

  lcd_byte(0x33,LCD_CMD)

  lcd_byte(0x32,LCD_CMD)

  lcd_byte(0x28,LCD_CMD)

  lcd_byte(0x0C,LCD_CMD)  

  lcd_byte(0x06,LCD_CMD)

  lcd_byte(0x01,LCD_CMD)  

def lcd_string(message):

  # Send string to display

  message = message.ljust(LCD_WIDTH," ")  

  for i in range(LCD_WIDTH):

    lcd_byte(ord(message[i]),LCD_CHR)

def lcd_byte(bits, mode):

  # Send byte to data pins

  # bits = data

  # mode = True  for character

  #        False for command

  GPIO.output(LCD_RS, mode) # RS

  # High bits

  GPIO.output(LCD_D4, False)

  GPIO.output(LCD_D5, False)

  GPIO.output(LCD_D6, False)

  GPIO.output(LCD_D7, False)

  if bits&0x10==0x10:

    GPIO.output(LCD_D4, True)

  if bits&0x20==0x20:

    GPIO.output(LCD_D5, True)

  if bits&0x40==0x40:

    GPIO.output(LCD_D6, True)

  if bits&0x80==0x80:

    GPIO.output(LCD_D7, True)

  # Toggle 'Enable' pin

  time.sleep(E_DELAY)    

  GPIO.output(LCD_E, True)  

  time.sleep(E_PULSE)

  GPIO.output(LCD_E, False)  

  time.sleep(E_DELAY)      

  # Low bits

  GPIO.output(LCD_D4, False)

  GPIO.output(LCD_D5, False)

  GPIO.output(LCD_D6, False)

  GPIO.output(LCD_D7, False)

  if bits&0x01==0x01:

    GPIO.output(LCD_D4, True)

  if bits&0x02==0x02:

    GPIO.output(LCD_D5, True)

  if bits&0x04==0x04:

    GPIO.output(LCD_D6, True)

  if bits&0x08==0x08:

    GPIO.output(LCD_D7, True)

  # Toggle 'Enable' pin

  time.sleep(E_DELAY)    

  GPIO.output(LCD_E, True)  

  time.sleep(E_PULSE)

  GPIO.output(LCD_E, False)  

  time.sleep(E_DELAY)   

if __name__ == '__main__':

  main()

the output look like this